Updates to digital content of all types are delivered via the cloud with increased frequency. Whereas some software packages would be updated once per year, or with even less frequency, it is now common for software developers to provide updates on a monthly basis or even faster than that. Other types of digital content, such as mapping databases and media libraries, are also updated with increased frequency.
In the past, updates to applications could be accomplished by downloading and installing a new installation package. A drawback to this technique was that a user's customization of an application program could be lost when new files in the installation package replaced older versions of the files. Another drawback was the large size of some installation packages, which could consume considerable amounts of time and bandwidth.
In many cases, the difference in files or binaries from one version of an application to another would not vary by much, making the full-installation process even less efficient. Even within binaries that did change from one version to the next, the change could be minimal. These and other drawbacks were mitigated by the development of patching. With patching, a limited set of files in an application package are targeted for updating, thereby limiting how many files need to be downloaded.
Differential compression technologies like binary delta compression can be leveraged to reduce the overall size of an update package, whether it includes patch files or complete files. Binary delta compression allows only the difference between old and new files to be downloaded during the update process. Thus, an update package may include a delta file that brings an old version of a file up-to-date with respect to a new version of the file, without having to download a complete version of the file.
While patching and differential compression technologies may improve the performance of a particular update, developers are confronted with a new situation due to the rapidity with which updates are created for digital content packages. Because updates are produced with greater frequency, the range of possible update states has expanded. To continue with present update paradigms implies that more and more delta files will need to be maintained in order to support all of the possible update states.